Not applicable.
1. Field of the Invention
This invention relates to the reconstitution of vascular circulation in a cadaver as a mechanism for study of the vascular function, research and teaching of surgical procedures and general medical training. In addition, this invention aids in the development and evaluation of new medical devices using techniques for reconstituting the vascular flow of a fluid simulating blood in a fresh (as opposed to an embalmed) cadaver.
2. Description of the Related Art
Training physicians and other medical care personnel and surgical associates for performing specific surgeries requires an appropriate model system. It is highly desirable for medical trainees to be able to practice and hone their skills on a model system, rather than on a live person in need of a particular treatment. Similarly, both the development of and new medical devices benefit from testing on a model system. Verification of physical and operating parameters of the device, development of surgical procedures for implantation of the device and training of medical care personnel to learn how to place and use these devices in a body are materially improved if there is a close model of the in vivo human system available for these activities. Indeed, there is the potential for a great deal of harm to a patient if the physician has not had the appropriate training or a particular device has not been appropriately evaluated and its performance characteristics verified. This is especially true for physicians and devices related to the endovascular system.
As the field of endovascular intervention steadily increases, there is an increasing need to train physicians and other surgical associates to perform new surgical techniques and to use new interventive devices. The new surgical techniques and new devices require training and practice on the part of the physicians and other surgical associates. In fact, the process of development of such new devices themselves is enhanced and facilitated with the ability to place prototypes into an xe2x80x9cin vivoxe2x80x9d environment, first to refine the physical parameters of the device and then to predict efficacy and utility before they are used on a live patient. All of these needs require an appropriate model system for replicating the implantation and device function prior to the implantation in a human.
To date, the only models available for this purpose involve either plastic models perfused with water and built to imitate the human vascular tree, or live animal models. For example, U.S. Pat. No. 5,632,623 discloses a mock circulation system having a plurality of channels formed within a housing to represent the arteries, veins and organs of a human circulatory system. The U.S. Pat. No. 5,632,623 system uses an artificial ventricle such as the type which are implanted in experimental animals including humans. Unfortunately, plastic models like the U.S. Pat. No. 5,632,623 model, do not have the same feel as human tissues or the same strength. Thus, testing devices on plastic model systems often does not recreate the situations found in human beings.
Animal models also have significant disadvantages. A major disadvantage is that the animals often differ significantly from humans in terms of their vascular anatomy as well as in the size of their vessels. Thus, training and testing on animal systems does not closely simulate the situations a medical associate or a medical device would encounter in a human body.
Life-like human models are more appropriate than plastic or animal models for practice and training purposes and could also accelerate the testing of new devices. While various systems using fresh human cadavers have been described previously, these systems are designed to embalm a body, not to reestablish circulation in isolated and discrete circuits of the body. For example, U.S. Pat. Nos. 2,369,694, 2,388,337, 2,401,849 and 2,462,617 all describe methods and pumps for preparing a cadaver for a burial which includes forcing the liquid embalming fluid into a body. They do not establish any type of circulation throughout the body, and in particular they do not isolate or re-establish any specific circulatory circuit.
Other systems for use on human organs are designed to preserve the human organs for eventual transplantation. For example, U.S. Pat. No.5,066,578 describes the perfusion of human organs such as liver, kidney, pancreas, spleen, brain, embryo, testicles, ovaries, lung or heart-lung complex with a specific physiological preservation solution. Unlike the instant invention, this method involves the practice of isolating and perfusing organs separate and away from the natural circulatory environment of the human body. Such approach specifically does not use the human body""s own circulatory circuits for reconstituting or emulating circulation. U.S. Pat. No. 4,666,425 (reexamination certificate issued Feb. 25, 1992 in which all 20 claims were canceled) describes the use of a device to supply a discorped head with oxygenated blood and nutrients. Similar to the U.S. Pat. No. 5,066,578 patent, the methods described in the U.S. Pat. No. 4,666,425 patent distinctly do not use the human body""s own circulatory circuits to maintain the circulation.
The inventive method provides a model system which can be used to isolate specific naturally occurring vascular circuits for both teaching and device development and evaluation purposes. The method has been designed to overcome the prior art problems of the plastic and non-human animal models by reconstituting circulation in the major vessels of a fresh, non-embalmed, non-heart-beating human cadaver.
Fresh, frozen cadavers are readily available for scientific investigation. By reconstituting, or simulating, the normal circulation patterns on these fresh cadavers, medical care personnel can develop, evaluate and practice specific endovascular procedures, as well as facilitate development and evaluation of various endovascular devices. Using actual human bodies offers the significant advantage of allowing the practitioner/trainee to operate on a model having the actual size and placement of the human vessels, as well as provide the realism that a plastic model necessarily lacks. Since actual human anatomy is used, this system provides a life-like training and testing situation.
The system of the instant invention provides at least a three-fold benefit: 1) a superior model system for research and development of new intra-operative techniques, 2) acceleration of the development of medical devices, particularly those which meet the United States Food and Drug Administration (FDA) guidelines, and 3) a powerful teaching tool so as to accelerate the learning curve of physicians and other surgical associates. Additionally, the inventive system further advances the knowledge, understanding and techniques associated with reconstituting circulation in a cadaver. This can lead to new methodologies in device research, including vascular stents, aortic devices, catheter and other vascular based interventional studies.